jwx is a Go library implementing JOSE security standards for signing, encrypting, parsing, and verifying JSON-based messages and tokens such as JWTs, JWSs, JWEs, and JWKs. Go developers use it to add authentication and related cryptographic protocols to products, and the catalogue includes guidance for assistants helping developers work with its version 4 API.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add lestrrat-go/jwx --skill guidegit clone --depth 1 https://github.com/lestrrat-go/jwxWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/lestrrat-go/jwx/guide)<a href="https://agentmods.dev/skills/lestrrat-go/jwx/guide"><img src="https://agentmods.dev/badge/skills/lestrrat-go/jwx/guide/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/lestrrat-go/jwx/guide"><img src="https://agentmods.dev/badge/skills/lestrrat-go/jwx/guide.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00061 | $0.06294 |
| Opus 5.5 | $0.00024 | $0.02518 |
| Sonnet 5.5 | $0.00012 | $0.01259 |
| Haiku 4.5 | $0.00006 | $0.00629 |
Grade A, and why
jwx-guide-v4 scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 388 lines — stays where its author put it; the contents beside it link to each section on GitHub.
jwx-guide-v4
This skill helps you assist Go developers who are using github.com/lestrrat-go/jwx/v4 in their own projects. It is scoped to v4 only. There is no equivalent skill for v3 or v2; for those, work from the version's own docs/ directory and pkg.go.dev. Do not apply v4 rules to a v3 or v2 codebase — the jwa identifiers are constants there, not functions, and the jwk and error APIs differ.
Where to look things up
You will not have this repository checked out. To verify an API claim before answering, use these sources, in order of preference:
- Go module cache — if the user's project depends on jwx, the source is on disk:
This directory contains the full source tree includingecho "$(go env GOMODCACHE)/github.com/lestrrat-go/jwx/v4@$(go list -m -f '{{.Version}}' github.com/lestrrat-go/jwx/v4)"docs/,jwt/,jws/,jwe/,jwk/,jwa/. - pkg.go.dev — canonical API reference for any exported symbol:
https://pkg.go.dev/github.com/lestrrat-go/jwx/v4https://pkg.go.dev/github.com/lestrrat-go/jwx/v4/jwt(etc. per subpackage)
- GitHub — narrative documentation lives at the repo:
https://github.com/lestrrat-go/jwx/blob/develop/v4/docs/01-jwt.mdhttps://github.com/lestrrat-go/jwx/blob/develop/v4/docs/02-jws.mdhttps://github.com/lestrrat-go/jwx/blob/develop/v4/docs/03-jwe.mdhttps://github.com/lestrrat-go/jwx/blob/develop/v4/docs/04-jwk.mdhttps://github.com/lestrrat-go/jwx/blob/develop/v4/docs/10-extensions.mdhttps://github.com/lestrrat-go/jwx/blob/develop/v4/docs/99-faq.md
- Examples repo — runnable usage patterns. The repo's
README.mdis a topical index that maps "what do I want to do" → "which*_example_test.gofile." Fetch the README first when looking for an example by topic; then fetch the linked file:https://github.com/jwx-go/examples/blob/develop/v4/README.md
When the user's question goes beyond the patterns in this skill (custom claim types, JWE recipients with per-recipient headers, custom key providers, base64 backend swap, performance tuning), fetch from these sources rather than guessing.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 11d ago Changed · +27 lines f2c537076aaa
- 15d ago Changed · +2 lines fedccffca52b
- 28d ago Changed · +29 lines f0cb4072f0f6
- 1mo ago Changed · +16 lines 9caac70b00cb
- 1mo ago First seen · 314 lines · 61 tokens per session scan A e8e9bcf280e9
jwx-guide-v4 is a skill published in the GitHub repository lestrrat-go/jwx (2,440 stars, last pushed yesterday), licensed MIT. It adds 61 tokens to every session and 6,294 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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